Oil sucking into airbox

I have a 2000 XR650R, Bike has had no problems until this past weekend. Started up on the first kick then after about 3 minutes of running oil started pouring from the side cover drain. It appears the oil is either being sucked out of the crancase through the breather or I have lost a ring and are getting blow by. Bike still has plenty of compression and starts right up so I do not think it is the rings. I did just top off the oil level but the dip stick read correctly. Any ideas before I tear into the engine?

Check your manual and then check the oil per the instructions. The chance of you breaking something internally just after topping off the oil is very low. I would just about bet that the oil is overfull. Before I tore anything apart I would check per the manual.


Sounds like you put too much oil in the engine. Too much oil will cause this to happen. If the engine is cold or has been cooling off for 15+ minutes, the oil level will appear too low. You must check your oil level right after you turn your engine off while its still hot to get an accurate reading, otherwise you risk putting in too much oil.

I checked the oil and it no longer shows on the dipstick (it’s all in the airbox now I guess). I started it up (first kick) and rode up the street about 50 yards and back. When I stopped oil was again pouring out the airbox drain. I have heard rumor of a screen filter somewhere on the bike. Is it possible this is clogged causing the oil pressure to build? If so anyone know where the screen is on the bike?

Originally posted by bbarer:

...If so anyone know where the screen is on the bike?

There's two wire mesh strainer screens in the oil system from what I know (excluding the oil filter). One is located at the bottom inside of the right crackcase cover between the clutch and primary drive gear (aboout 5 o'clock from the clutch) and the other is a thimble like screen fitted inside the oil down tube. While investigating this, it may be a good time to change the oil filter as well. Make sure you install the oil filter with the outside mark facing outward.

The screen inside the right crankcase cover should be pretty clean, but the downtube screen will get dirty. If you've never cleaned your downtube screen, then don't be surprised if its full of metal filings. Mine had metal filings on it within the first hundred miles and I've talked with a number of people who have shared the same experience, so don't get too worried if that's what you find. The amount of metal filings has greatly decreased with each oil change, but this is certainly an area you should check out if you haven't done so already.

If there's too much oil in the frame, it will come out through the crank case breather that's is vented to the airbox. If there's too much pressure or if this vent hose is partially or fully blocked, it can blow out your counter shaft seal and from there your bike will quickly loose the majority of its oil supply, which could be potentially disasterous to your engine. Some people have reported that their breather tube, which is routed underneath the seat has been pinched when they re-installed their seat, so be careful of this when putting things back together to make sure your hose has enough clearance to avoid this other problem.

[ August 13, 2002: Message edited by: qadsan ]

I have the external site tube on my 650R and it shows just how the oil fills that tank. It is difficult to get an accurate reading with the dip stick. My bet is that are over full. Dump your oil and refill with the correct amount.

I agree with the other posters. Change filter,

clean downtube screen ( I use gasoline ) then

fill with 1800cc's of oil. I put in 1200cc's,

fire her up for ten seconds only, then put in

remaining 600ccs. This takes me to one inch

from top mark on dipstick. There is no need

to add extra oil to bring it to the top mark.

cheers, Craig


Sounds to me, you do not know where your oil level really is. Check the site below and it will explain the oil capicity and oil checking procedure. Has a bunch of other neat stuff.

Click on American Hondas race tips and look up the oil check steps including letting the bike idle before killing the engine. These guys are the super experts.

http://www.xr650r.net/ :)

[ August 15, 2002: Message edited by: Mainjet2001 ]

Thanks, guys for all the help. My oil was definately over full and the screen in the down tube was quite clogged. Again thanks for the help.

bbarer, Dont feel bad I had overfilled my 86 600 because I always checked it when it was cold. Of course it was always low so I would top it off. It puked oil out of the crank tube and would not stay running. I took it to the shop and had the carbs cleaned and they did not want to try to start it because it had kicked back on one of them and hurt their leg. I finally went down there and agreed to kick it for them. Before I did they wanted to check the timing when they took off the inspection covers oil poured out. We drained the oil. Refilled and guess what. It ran better then ever. Be glad you figured it out on your own and did not have to feel like a total dumba$$ at your local shop.

Did the same thing over filled the BRP when it was cold it puked out oil for a couple of rides. Then stopped. Funny it never overheated then.

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